/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.sql;

/**
 * An input stream that contains a stream of values representing an
 * instance of an SQL structured type or an SQL distinct type.
 * This interface, used only for custom mapping, is used by the driver
 * behind the scenes, and a programmer never directly invokes
 * <code>SQLInput</code> methods. The <i>reader</i> methods
 * (<code>readLong</code>, <code>readBytes</code>, and so on)
 * provide a way  for an implementation of the <code>SQLData</code>
 * interface to read the values in an <code>SQLInput</code> object.
 * And as described in <code>SQLData</code>, calls to reader methods must
 * be made in the order that their corresponding attributes appear in the
 * SQL definition of the type.
 * The method <code>wasNull</code> is used to determine whether
 * the last value read was SQL <code>NULL</code>.
 * <P>When the method <code>getObject</code> is called with an
 * object of a class implementing the interface <code>SQLData</code>,
 * the JDBC driver calls the method <code>SQLData.getSQLType</code>
 * to determine the SQL type of the user-defined type (UDT)
 * being custom mapped. The driver
 * creates an instance of <code>SQLInput</code>, populating it with the
 * attributes of the UDT.  The driver then passes the input
 * stream to the method <code>SQLData.readSQL</code>, which in turn
 * calls the <code>SQLInput</code> reader methods
 * in its implementation for reading the
 * attributes from the input stream.
 *
 * @since 1.2
 */

public interface SQLInput {

  //================================================================
  // Methods for reading attributes from the stream of SQL data.
  // These methods correspond to the column-accessor methods of
  // java.sql.ResultSet.
  //================================================================

  /**
   * Reads the next attribute in the stream and returns it as a <code>String</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  String readString() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>boolean</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>false</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  boolean readBoolean() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>byte</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  byte readByte() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>short</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  short readShort() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as an <code>int</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  int readInt() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>long</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  long readLong() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>float</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  float readFloat() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>double</code>
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>0</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  double readDouble() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>java.math.BigDecimal</code>
   * object in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.math.BigDecimal readBigDecimal() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as an array of bytes
   * in the Java programming language.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  byte[] readBytes() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>java.sql.Date</code> object.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.sql.Date readDate() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>java.sql.Time</code> object.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.sql.Time readTime() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>java.sql.Timestamp</code>
   * object.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.sql.Timestamp readTimestamp() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a stream of Unicode characters.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.io.Reader readCharacterStream() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a stream of ASCII characters.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.io.InputStream readAsciiStream() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a stream of uninterpreted
   * bytes.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  java.io.InputStream readBinaryStream() throws SQLException;

  //================================================================
  // Methods for reading items of SQL user-defined types from the stream.
  //================================================================

  /**
   * Reads the datum at the head of the stream and returns it as an
   * <code>Object</code> in the Java programming language.  The
   * actual type of the object returned is determined by the default type
   * mapping, and any customizations present in this stream's type map.
   *
   * <P>A type map is registered with the stream by the JDBC driver before the
   * stream is passed to the application.
   *
   * <P>When the datum at the head of the stream is an SQL <code>NULL</code>,
   * the method returns <code>null</code>.  If the datum is an SQL structured or distinct
   * type, it determines the SQL type of the datum at the head of the stream.
   * If the stream's type map has an entry for that SQL type, the driver
   * constructs an object of the appropriate class and calls the method
   * <code>SQLData.readSQL</code> on that object, which reads additional data from the
   * stream, using the protocol described for that method.
   *
   * @return the datum at the head of the stream as an <code>Object</code> in the Java programming
   * language;<code>null</code> if the datum is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  Object readObject() throws SQLException;

  /**
   * Reads an SQL <code>REF</code> value from the stream and returns it as a
   * <code>Ref</code> object in the Java programming language.
   *
   * @return a <code>Ref</code> object representing the SQL <code>REF</code> value at the head of
   * the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  Ref readRef() throws SQLException;

  /**
   * Reads an SQL <code>BLOB</code> value from the stream and returns it as a
   * <code>Blob</code> object in the Java programming language.
   *
   * @return a <code>Blob</code> object representing data of the SQL <code>BLOB</code> value at the
   * head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  Blob readBlob() throws SQLException;

  /**
   * Reads an SQL <code>CLOB</code> value from the stream and returns it as a
   * <code>Clob</code> object in the Java programming language.
   *
   * @return a <code>Clob</code> object representing data of the SQL <code>CLOB</code> value at the
   * head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  Clob readClob() throws SQLException;

  /**
   * Reads an SQL <code>ARRAY</code> value from the stream and returns it as an
   * <code>Array</code> object in the Java programming language.
   *
   * @return an <code>Array</code> object representing data of the SQL <code>ARRAY</code> value at
   * the head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  Array readArray() throws SQLException;

  /**
   * Retrieves whether the last value read was SQL <code>NULL</code>.
   *
   * @return <code>true</code> if the most recently read SQL value was SQL <code>NULL</code>;
   * <code>false</code> otherwise
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  boolean wasNull() throws SQLException;

  //---------------------------- JDBC 3.0 -------------------------

  /**
   * Reads an SQL <code>DATALINK</code> value from the stream and returns it as a
   * <code>java.net.URL</code> object in the Java programming language.
   *
   * @return a <code>java.net.URL</code> object.
   * @throws SQLException if a database access error occurs, or if a URL is malformed
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.4
   */
  java.net.URL readURL() throws SQLException;

  //---------------------------- JDBC 4.0 -------------------------

  /**
   * Reads an SQL <code>NCLOB</code> value from the stream and returns it as a
   * <code>NClob</code> object in the Java programming language.
   *
   * @return a <code>NClob</code> object representing data of the SQL <code>NCLOB</code> value at
   * the head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  NClob readNClob() throws SQLException;

  /**
   * Reads the next attribute in the stream and returns it as a <code>String</code>
   * in the Java programming language. It is intended for use when
   * accessing  <code>NCHAR</code>,<code>NVARCHAR</code>
   * and <code>LONGNVARCHAR</code> columns.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  String readNString() throws SQLException;

  /**
   * Reads an SQL <code>XML</code> value from the stream and returns it as a
   * <code>SQLXML</code> object in the Java programming language.
   *
   * @return a <code>SQLXML</code> object representing data of the SQL <code>XML</code> value at the
   * head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  SQLXML readSQLXML() throws SQLException;

  /**
   * Reads an SQL <code>ROWID</code> value from the stream and returns it as a
   * <code>RowId</code> object in the Java programming language.
   *
   * @return a <code>RowId</code> object representing data of the SQL <code>ROWID</code> value at
   * the head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  RowId readRowId() throws SQLException;

  //--------------------------JDBC 4.2 -----------------------------

  /**
   * Reads the next attribute in the stream and returns it as an
   * {@code Object} in the Java programming language. The
   * actual type of the object returned is determined by the specified
   * Java data type, and any customizations present in this
   * stream's type map.
   *
   * <P>A type map is registered with the stream by the JDBC driver before the
   * stream is passed to the application.
   *
   * <P>When the attribute at the head of the stream is an SQL {@code NULL}
   * the method returns {@code null}. If the attribute is an SQL
   * structured or distinct
   * type, it determines the SQL type of the attribute at the head of the stream.
   * If the stream's type map has an entry for that SQL type, the driver
   * constructs an object of the appropriate class and calls the method
   * {@code SQLData.readSQL} on that object, which reads additional data from the
   * stream, using the protocol described for that method.
   * <p>
   * The default implementation will throw {@code SQLFeatureNotSupportedException}
   *
   * @param <T> the type of the class modeled by this Class object
   * @param type Class representing the Java data type to convert the attribute to.
   * @return the attribute at the head of the stream as an {@code Object} in the Java programming
   * language;{@code null} if the attribute is SQL {@code NULL}
   * @throws SQLException if a database access error occurs
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.8
   */
  default <T> T readObject(Class<T> type) throws SQLException {
    throw new SQLFeatureNotSupportedException();
  }
}
